CODEWITHSUNDEEP
swiftios8
Sap
Sap

Reputation: 848

Swift/IOS8 error: "fatal error: Can't unwrap Optional.None"

I know there are already a couple issues on this, but I can't figure it out. The previous solved issues would suggest that 'profileViewController' is nil, but I don't know why that would be the case. The UI is completely programmatic, no IB. Getting:

"fatal error: Can't unwrap Optional.None"

on pushViewController() in the following code:

class FavoritesViewController: UIViewController {

    init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
        // Custom initialization
        self.title = "Favorites"
        self.tabBarItem.image = UIImage(named: "MikeIcon")
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        self.view.backgroundColor = UIColor.redColor()

        let profileButton = UIButton.buttonWithType(.System) as UIButton
        profileButton.frame = CGRectMake(60, 300, 200, 44)
        profileButton.setTitle("View Profile", forState: UIControlState.Normal)
        profileButton.addTarget(self, action: "showProfile:", forControlEvents: UIControlEvents.TouchUpInside)
        self.view.addSubview(profileButton)

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func showProfile(sender: UIButton) {
        let profileViewController = ProfileViewController(nibName: nil, bundle: nil)
        self.navigationController.pushViewController(profileViewController, animated: true)

    }

Here's the relevant portion of AppDelegate.swift:

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        // Override point for customization after application launch.

        let feedViewController = FeedViewController(nibName: nil, bundle: nil)
        let favoritesViewController = FavoritesViewController(nibName: nil, bundle: nil)
        let profileViewController = ProfileViewController(nibName: nil, bundle: nil)

        let tabBarController = UITabBarController()
        self.window!.rootViewController = tabBarController

        tabBarController.viewControllers = [feedViewController, favoritesViewController, profileViewController]        


        self.window!.backgroundColor = UIColor.whiteColor()
        self.window!.makeKeyAndVisible()
        return true
    }

screenshot

Upvotes: 4

Views: 788

Answers (1)

kurtn718
kurtn718

Reputation: 751

Is the Navigation Controller object self.navigationController nil?

The variable type on the navigationController property is an unwrapped optional. If your View Controller is not inside a UINavigationController that would be the problem.

To prevent the crash code along the following lines should be written:

if (self.navigationController)
{
    self.navigationController.pushViewController(profileViewController, animated: true) 
}

Alternatively you could write the code as:

self.navigationController?.pushViewController(profileViewController, animated: true)

The ? operator will prevent any further code from being executed, if self.navigationController evaluates to nil.

Upvotes: 2

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